The cost isn't so much the materials themselves as the regulatory burden imposed by them. You need to guard them indefinitely even after the plant is shut down. You need to inspect them regularly. If the waste is a mile underground under a couple megatons of rock and concrete then it's not a lasting cost to the company that built it.

> The cost isn't so much the materials themselves as the regulatory burden imposed by them. You need to guard them indefinitely even after the plant is shut down.

These are all issues for fossil fuel extraction as well, and I have bad news for you about how this problem is currently handled.

In my opinion, the biggest problem with fossil fuel extraction is that it is slowly destroying our biosphere.

Exactly. Tons of abandoned oil wells left for the taxpayers to clean up. But of course we can’t demand that all new wells post bonds for the cleanup costs in advance, that would make them unprofitable.

It depends on what you define as long-term. For a few decades, with proper inspections, sure. For the geological time frames needed for nuclear waste disposal, definitely not.